Proteus mirabilis UreR coordinates cellular functions required for urease activity

A hallmark of Proteus mirabilis infection of the urinary tract is the formation of stones. The ability to induce urinary stone formation requires urease, a nickel metalloenzyme that hydrolyzes urea. This reaction produces ammonia as a byproduct, which can serve as a nitrogen source and weak base that raises the local pH. The resulting alkalinity induces the precipitation of ions to form stones. Transcriptional regulator UreR activates expression of urease genes in a urea-dependent manner. Thus, urease genes are highly expressed in the urinary tract where urea is abundant. Production of mature urease also requires the import of nickel into the cytoplasm and its incorporation into the urease apoenzyme. Urease accessory proteins primarily acquire nickel from one of two nickel transporters and facilitate incorporation of nickel to form mature urease. In this study, we performed a comprehensive RNA-seq to define the P. mirabilis urea-induced transcriptome as well as the UreR regulon. We identified UreR as the first defined regulator of nickel transport in P. mirabilis. We also offer evidence for the direct regulation of the Ynt nickel transporter by UreR. Using bioinformatics, we identified UreR-regulated urease loci in 15 Morganellaceae family species across three genera. Additionally, we located two mobilized UreR-regulated urease loci that also encode the ynt transporter, implying that UreR regulation of nickel transport is a conserved regulatory relationship. Our study demonstrates that UreR specifically regulates genes required to produce mature urease, an essential virulence factor for P. mirabilis uropathogenesis.

IMPORTANCE

Catheter-associated urinary tract infections (CAUTIs) account for over 40% of acute nosocomial infections in the USA and generate $340 million in healthcare costs annually. A major causative agent of CAUTIs is Proteus mirabilis, an understudied Gram-negative pathogen noted for its ability to form urinary stones via the activity of urease. Urease mutants cannot induce stones and are attenuated in a murine UTI model, indicating this enzyme is essential to P. mirabilis pathogenesis. Transcriptional regulation of urease genes by UreR is well established; here, we expand the UreR regulon to include regulation of nickel import, a function required to produce mature urease. Furthermore, we reflect on the role of urea catalysis in P. mirabilis metabolism and provide evidence for its importance.

Defining a Molecular Signature for Uropathogenic versus Urocolonizing Escherichia coli: The Status of the Field and New Clinical Opportunities

Urinary tract infections (UTIs) represent a major burden across the population, although key facets of their pathophysiology and host interaction remain unclear. Escherichia coli epitomizes these obstacles: this gram-negative bacterial species is the most prevalent agent of UTIs worldwide and can also colonize the urogenital tract in a phenomenon known as asymptomatic bacteriuria (ASB). Unfortunately, at the level of the individual E. coli strains, the relationship between UTI and ASB is poorly defined, confounding our understanding of microbial pathogenesis and strategies for clinical management. Unlike diarrheagenic pathotypes of E. coli, the definition of uropathogenic E. coli (UPEC) remains phenomenologic, without conserved phenotypes and known genetic determinants that rigorously distinguish UTI- and ASB-associated strains. This article provides a cross-disciplinary review of the current issues from interrelated mechanistic and diagnostic perspectives and describes new opportunities by which clinical resources can be leveraged to overcome molecular challenges. Specifically, we present our work harnessing a large collection of patient-derived isolates to identify features that do (and do not) distinguish UTI- from ASB-associated E. coli strains. Analyses of biofilm formation, previously reported to be higher in ASB strains, revealed extensive phenotypic heterogeneity that did not correlate with symptomatology. However, metabolomic experiments revealed distinct signatures between ASB and cystitis isolates, including in the purine pathway (previously shown to be critical for intracellular survival during acute infection). Together, these studies demonstrate how large-scale, wild-type approaches can help dissect the physiology of colonization versus infection, suggesting that the molecular definition of UPEC may rest at the level of global bacterial metabolism.

Respiratory Heterogeneity Shapes Biofilm Formation and Host Colonization in Uropathogenic Escherichia coli

Biofilms are multicellular bacterial communities encased in a self-secreted extracellular matrix comprised of polysaccharides, proteinaceous fibers, and DNA. Organization of these components lends spatial organization to the biofilm community such that biofilm residents can benefit from the production of common goods while being protected from exogenous insults. Spatial organization is driven by the presence of chemical gradients, such as oxygen. Here we show that two quinol oxidases found in Escherichia coli and other bacteria organize along the biofilm oxygen gradient and that this spatially coordinated expression controls architectural integrity. Cytochrome bd, a high-affinity quinol oxidase required for aerobic respiration under hypoxic conditions, is the most abundantly expressed respiratory complex in the biofilm community. Depletion of the cytochrome bd-expressing subpopulation compromises biofilm complexity by reducing the abundance of secreted extracellular matrix as well as increasing cellular sensitivity to exogenous stresses. Interrogation of the distribution of quinol oxidases in the planktonic state revealed that ∼15% of the population expresses cytochrome bd at atmospheric oxygen concentration, and this population dominates during acute urinary tract infection. These data point toward a bet-hedging mechanism in which heterogeneous expression of respiratory complexes ensures respiratory plasticity of E. coli across diverse host niches.IMPORTANCE Biofilms are multicellular bacterial communities encased in a self-secreted extracellular matrix comprised of polysaccharides, proteinaceous fibers, and DNA. Organization of these components lends spatial organization in the biofilm community. Here we demonstrate that oxygen gradients in uropathogenic Escherichia coli (UPEC) biofilms lead to spatially distinct expression programs for quinol oxidases-components of the terminal electron transport chain. Our studies reveal that the cytochrome bd-expressing subpopulation is critical for biofilm development and matrix production. In addition, we show that quinol oxidases are heterogeneously expressed in planktonic populations and that this respiratory heterogeneity provides a fitness advantage during infection. These studies define the contributions of quinol oxidases to biofilm physiology and suggest the presence of respiratory bet-hedging behavior in UPEC.

Salivary but not plasma cortisone tracks the plasma cortisol response to exercise: effect of time of day

INTRODUCTION

The cortisol, cortisone, corticosterone, and CBG responses to exercise in the AM and PM have not been described. This study examined the response of these glucocorticoids and CBG to intense exercise in 12 endurance-trained men in plasma (Pl) and saliva (Sa).

METHODS

Each subject completed treadmill exercise in the morning and evening. Paired blood and Sa samples were obtained at rest before and after exercise.

RESULTS

Significant time effect existed for Pl-cortisol and Sa-cortisol from baseline in the AM and PM (p < 0.01). Pl-cortisone and CBG significantly increased in the PM (p < 0.01). Pl-corticosterone increased in the AM and PM (p < 0.01). Unlike Pl-cortisone, Sa-cortisone was significantly higher in the AM compared to the PM, increasing in the AM and PM (All p < 0.01). Strong associations were found between Pl-cortisol and Sa-cortisol (r = 0.81, p < 0.0001), Pl-cortisol and Sa-cortisone (r = 0.81, p < 0.0001).

CONCLUSIONS

(1) Intense EX induces a similar increase in Pl-cortisone (~90 %) and corticosterone (~200 %) in the AM and PM, whereas exercise increases CBG in the PM, but not in the AM; (2) vigorous exercise increases Sa-cortisone; (3) Sa-cortisone and cortisol are equally strongly correlated to Pl-cortisol, suggesting a significant role for Sa-cortisone as a novel marker of free cortisol during exercise.

Temporal indication of marijuana use can be estimated from plasma and urine concentrations of delta9-tetrahydrocannabinol, 11-hydroxy-delta9-tetrahydrocannabinol, and 11-nor-delta9-tetrahydrocannabinol-9-carboxylic acid

Current technology establishes marijuana use based upon detection of the pharmacologically inactive cannabinoid metabolite (11-nor-delta9-carboxy-tetrahydrocannabinol-9-carboxylic acid, THC-COOH) in urine. No accurate prediction of time of use is possible because THC-COOH has a half-life of 6 days. To determine if a temporal relationship between marijuana use and metabolite excretion patterns could be established, eight healthy user-volunteers (18-35 years old) smoked marijuana cigarettes containing 0% (placebo), 1.77%, and 3.58% delta9-tetrahydrocannabinol (THC). Plasma and urine were collected prior to smoking, 5 min after smoking, and hourly thereafter for 8 h for measurement of cannabinoid concentrations by gas chromatography-mass spectrometry. Mathematical models proposed for determination of recent marijuana use were applied to data from this study and verified the temporal use of marijuana. One subject, who later admitted chronic marijuana use (urine baseline THCCOOH, 529.2 ng/mL; plasma, 75.5 ng/mL), excreted 8beta-dihydroxy-THC, peaking 2 h postsmoking (92.3 ng/mL). Urinary THC, the psychoactive component of marijuana, concentrations peaked 2 h after smoking and declined to assay limit of detection (LOD) (1.5 ng/mL) by 6 h. 11-Hydroxy-delta9-tetrahydrocannabinol (11-OH-THC) and THCCOOH were detectable for the entire 8-h testing period but continued to decrease. Urinary concentrations of THC greater than 1.5 ng/mL suggests marijuana use during the previous 8-h time period.

Inadequacies of self-report data for exclusion criteria detection in marihuana research: an empirical case for multi-method direct examination screening

Stringent exclusion criteria in drug abuse research are necessary to protect against methodological confounds compromising the interpretation of findings. However, reliance on self-report screening may fail to detect important exclusion variables. We compared three levels of exclusion criteria screening in a study of neurophysiological/neurocognitive sequelae of chronic marihuana use in normals. LEVEL 1 (self-report) consisted of telephone pre-screening. LEVEL 2 (also self-report) involved in-depth personal interviews. LEVEL 3 consisted of several direct examination assessments including a medical/psychiatric examination by a board certified psychiatrist, eight weeks of twice per week urine drug screens, an EEG exam and eight hours of neuropsychological testing. Results indicated that 39.0% of subjects passing self-report screening had significant exclusion criteria findings that were only detected through LEVEL 3 direct examination procedures. Of all subjects found to have exclusion criteria after being provisionally accepted following LEVEL 1 telephone pre-screening, 55.7% were detected only through more rigorous LEVEL 3 direct examination screening methods.

Recurrent myelinoclastic diffuse sclerosis: a case report of a child with Schilder's variant of multiple sclerosis

Myelinoclastic diffuse sclerosis (MDS, Schilder's disease) is a rare CNS demyelinating disorder affecting mainly children and usually presenting as an intracranial mass lesion. We report the first case of recurrent intracranial MDS where the third episode of demyelination involved the cervical spinal cord. This may represent a subset of the disease, which should be considered as Schilder's variant (childhood form) of multiple sclerosis.

Cannabinoids in humans. II. The influence of three methods of hydrolysis on the concentration of THC and two metabolites in urine

Glucuronide conjugates of cannabinoids were previously identified in humans. For gas chromatographic-mass spectrometric (GC-MS) analysis of the unconjugated compounds in human urine, it is necessary to cleave the glucuronide moiety. Base hydrolysis and two forms of enzymatic hydrolysis were compared in this study to examine any quantitative differences between the hydrolysis methods. Human volunteers (n = 8) each smoked one marijuana cigarette containing 3.58% delta 9-tetrahydrocannabinol (THC) and submitted urine samples prior to smoking, 5 min after smoking, and hourly for 8 h thereafter. Urine (1 mL) was buffered to the optimum pH for each form of enzyme tested. beta-Glucuronidase from Escherichia coli (bacteria) or Helix pomatia (mollusk) was added to the specimens, followed by overnight incubation at 37 degrees C. Following hydrolysis, the samples were extracted using hexane-ethyl acetate (7:1) and derivatized with N,O-bis(trimethylsilyl)-trifluoroacetamide plus 1% trimethylchlorosilane, which converted the cannabinoids to their trimethylsilyl derivatives. GC-MS analysis revealed striking differences between the hydrolysis methods. Concentrations of unconjugated THC and 11-hydroxy-THC (11-OH-THC) using E. coli were significantly increased over all other methods tested (p < .05). These results demonstrate the species-dependent nature of glucuronidase activity in hydrolyzing THC and 11-OH-THC glucuronides and the ineffectiveness of base hydrolysis on these hydroxylated compounds. The need for further study to find the optimum conditions necessary for the complete hydrolysis of cannabinoid conjugates is suggested.

The effect of increasing doses of beta-agonists on airflow in patients with chronic airflow limitation

OBJECTIVE

To determine the increase in FEV1 associated with increasing doses of inhaled terbutaline and salbutamol, the reproducibility of the increase in FEV1, and the reproducibility of the associated optimal bronchodilator dose, in patients with chronic airflow limitation (CAL).

DESIGN

Double-blind, randomized, controlled trial examining spirometric response to cumulative doses of bronchodilators.

PATIENTS AND SETTING

Patients with clinical diagnosis of CAL, FEV1 below 70% predicted, and FEV1 to FVC ratio less than 0.7 after administration of bronchodilator recruited from secondary care respirology practices.

MEASURES OF OUTCOME

The estimates of maximum and optimal bronchodilation, as well as the associated drug dosages, were established in each patient on three occasions (twice on terbutaline and once on salbutamol). The 'optimal' drug dose was defined as the lowest dose associated with an FEV1 not exceeded by 50 ml on any other dose.

MAIN RESULTS

Thirty-five patients completed the trial. FEV1 improved from 0.93 to a maximum of 1.191 with terbutaline (average of the two administrations) and from 0.951 to 1.141 with inhaled salbutamol (difference in increase in FEV1 between terbutaline and salbutamol P = 0.006). In less than 50% of cases administration of more than four puffs of bronchodilator resulted in FEV1 increase by more than 50 ml. The average dose of salbutamol and terbutaline associated with optimal bronchodilation were 430 micrograms and 1160 micrograms respectively. Patients varied widely in the optimal dose. Estimates of optimal dose were not reproducible (intraclass correlation coefficient < 0.5).

CONCLUSION

Substantial incremental increase in FEV1 in response to increasing doses of beta-agonists beyond those commonly used in clinical practice is restricted to a minority of patients. Lack of reproducibility limits the clinical usefulness of establishing the optimal dose of beta-agonist for a given patient.

Early metabolic effects of sepsis in the preterm infant: lactic acidosis and increased glucose requirement

The effects of sepsis on carbohydrate metabolism were studied in preterm newborn infants (weight > 1.2 kg, appropriate for gestational age) without maternal endocrine problems who were being examined for infection. Plasma glucose, lactate, and insulin concentrations were measured at initial evaluation and then every 8 hours for a total of 48 hours. Blood, urine, and spinal fluid were obtained for culture and counterimmunoelectrophoresis. Dextrose was administered to each patient to maintain glucose levels in the normal range. Dextrose infusion rates were calculated in milligrams per kilogram per minute. Of the 29 infants, 6 had sepsis (positive culture and counterimmunoelectrophoresis results). Infants with sepsis had significant elevations of plasma lactate concentration (p < 0.003) but normal pH. The dextrose infusion rate was also significantly elevated in the infected infants (p < 0.01). No hypoglycemia or hyperglycemia was observed in either group. No significant difference in plasma insulin concentration was observed. We conclude that significant elevations in plasma lactate concentrations and dextrose infusion rate may be early clinical markers of neonatal sepsis in the first 48 hours of life.

c-myc, c-fos, and c-jun regulation in the regenerating livers of normal and H-2K/c-myc transgenic mice

We investigated the mechanisms of regulation of c-myc, c-fos, and c-jun at the early stages of liver regeneration in mice. We show that the transient increase in steady-state levels of c-myc mRNA at the start of liver regeneration is most probably regulated by posttranscriptional mechanisms. Although there was a marked increase in c-myc transcriptional initiation shortly after partial hepatectomy, a block in elongation prevented the completion of most transcripts. To gain further information on the mechanism of regulation of c-myc expression during liver regeneration, we used transgenic mice harboring the human c-myc gene driven by the H-2K promoter. In these animals, the murine c-myc responded to the growth stimulus generated by partial hepatectomy, whereas the expression of the transgene was constitutive and did not change in the regenerating liver. However, the mRNA from both genes increased markedly after cycloheximide injection, suggesting that the regulation of c-myc mRNA abundance in the regenerating liver differs from that occurring after protein synthesis inhibition. Furthermore, we show that in normal mice c-fos and c-jun mRNA levels and transcriptional rates increase within 30 min after partial hepatectomy. c-fos transcriptional elongation was restricted in nongrowing liver, but the block was partially relieved in the regenerating liver. Nevertheless, for both c-fos and c-jun, changes in steady-state mRNA detected after partial hepatectomy were much greater than the transcriptional increase. In the regenerating liver of H-2K/c-myc mice, c-fos and c-jun expression was diminished, whereas mouse c-myc expression was enhanced in comparison with that in nontransgenic animals.

Encapsulated nerve endings in murine dorsal ear skin

Encapsulated nerve endings in the hairy skin of mice were identified by means of cholinesterase histochemistry. They were especially numerous in the dorsal skin of the ear and where totals ranged from 150 to 597; clustering of corpuscles was an obvious feature. The use of silver impregnation as a counterstain revealed that clusters comprised one or more sets of lamellated corpuscles, each being attached to a single parent axon. The members of each set resembled one another morphologically. Corpuscles from different sets could be classified as simple, branched or coiled. In the hairy skin of cheek, trunk and hindlimb a much lower density of corpuscles was observed; they were all simple in form and occurred in small clusters.

Motor innervation of rodent diaphragm

In order to investigate the possibility of an intercostal nerve contribution to the motor innervation of the diaphragm, the phrenic nerve was interrupted unilaterally in the root of the neck in rats and mice and the pattern of innervation was later studied histologically. The results showed the phrenic nerve to be the sole source of motor innervation. The only contribution from intercostal nerves was to blood vessels and to intramuscular connective tissue.

Internodal segments in human laryngeal nerves

The laryngeal nerves of a recently deceased patient were examined in order to determine whether the prenatal elongation of the recurrent nerves (especially of the left) is accompanied by significant elongation of internodal segments among their myelinated fibres. No evidence was found to support this notion. In the nerve roots of the cauda equina, internodal elongation is known to accompany ascent of the spinal cord during fetal life. The difference in behaviour in the two cases seems to lie in the fact that the laryngeal nerves reach their final positions before myelination commences, whereas the spinal nerve roots elongate later, at a time when Schwann cell multiplication has largely ceased.

Extensive Volcanism Associated with the Separation of Australia and Antarctica

Alternating hard and soft layers characterize the Gull Rock and Tuit Members of the late Eocene Blanche Point Formation, South Australia. Originally the formation was mainly a mixture of volcanic ash, sponge spicules, and calcareous fossil remains, with hard layers produced later by selective silicification. It resembles Cretaceous sediments from western Europe and the eastern coast of the United States, and in each case it appears that alteration of volcanic ash produced smectite and clinoptilolite with release of silica that subsequently crystallized as opal-CT. The occurrence of similar deposits from New Zealand to as far west as Albany, Western Australia, indicates extensive volcanic activity south of Australia in the late Eocene resulting from rifting and separation from Antarctica.

Sources of innervation of the neuromuscular spindles in sternomastoid and trapezius

The sources of innervation of neuromuscular spindles in sternomastoid and trapezius have been investigated in rats and mice, by degeneration experiments. The entire motor supply, both extrafusal and intrafusal, to both muscles, was from the spinal accessory nerve. The sensory supply to the spindles in sternomastoid and rostral trapezius was from cervical spinal nerves, and to those in the caudal trapezius was from thoracic spinal nerves.

A method of staining basal-cell plasma membranes in epidermal sheets

An adenosine triphosphatase method was devised to stain basal epidermal cell plasma membranes in sheet preparations of humans, rat, mouse and guinea pig epidermis. The method is useful for direct observation of sizes, shapes, and numbers of basal epidermal cells.

The structure and source of lingual proprioceptors in the monkey

The proprioceptive innervation of the tounge has been investigated in the Cynamolgus monkey by silver impregnation methods following unilateral section of lingual, hypoglossal, and cervical nerves. Muscle spindles were constantly present in the intrinsic and extrinsic muscles. They varied greatly in number, averaged half the length of lumbrical spindles, and showed an unusual arrangement of chain fibre nuclei. Other, inconstant proprioceptors included tendon endings, Ruffini endings, Pacinian corpuscles, paciniform and lamellated endings. Topologically, the endings other than spindles were extra-muscular, so that the overall pattern of proprioceptive innervation resembled that of skeletal muscle in general. Lingual nerve section was without apparent effect on the proprioceptors. Section of the hypoglossal nerve at its point of entry into the tongue caused severe depletiion of ipsilateral proprioceptors and of fusimotor nerves. In the anterior tongue there was evidence of transmedian overlap by efferent and afferent axons contained in the hypoglossal nerve. Hypoglossal section at the skull base caused degeneration of fusimotor nerves but not of proprioceptors. Section of (a), the connexion of C2-C3 ventral rami with the hypoglossal, together with section of (b), the ramus descendens hypoglossi, coused depletion of lingual proprioceptors; again there was evidence of transmedian overlap. Procedures (a) or (b) alone had a lesser effect. It was concluded that lingual proprioceptive afferent fibres occupy the distal hypoglossal nerve, leaving it in the ramus descendens and in the C2-C3 connexion to enter the spinal cord via nerves C2 and C3.

Encapsulated nerve endings in hairy skin

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Follicular growth and innervation in hairless mice

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The intramscular ganglia of the cat's tongue

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